将日期从 Activity 传递到选项卡片段

Question

嗨，朋友们，我正在尝试将数组数据从 activity 传递到选项卡片段，但它给了我空指针异常，我正在使用 json 将数据存储到 getter和 setter 方法并尝试将该列表传递给 frgament 方法

Display.class

public static void toast(Context context, String display) { Toast.makeText(context, display, Toast.LENGTH_LONG).show(); }

我的错误

 java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.Resources android.content.Context.getResources()' on a null object reference

这是我的主要内容activity

public class HotelDetails extends AppCompatActivity {
    @BindView(R.id.hoteldetailedtoolbar)
    Toolbar hoteldetailedtoolbar;
    @BindView(R.id.hotelamentiestab)
    TabLayout hotelamentiestab;
    @BindView(R.id.hotelpager)
    ViewPager hotelpager;
    ArrayList<Hotel_image> hotelimg = new ArrayList<Hotel_image>();
    @BindView(R.id.hotelname)
    TextView hotelname;
    @BindView(R.id.hotelprice)
    TextView hotelprice;
    @BindView(R.id.roomtype)
    TextView roomtype;
    @BindView(R.id.whatsmakes)
    TextView whatsmakes;
    @BindView(R.id.needtoknow)
    TextView needtoknow;
    HotelImages hoteladapter;
    @BindView(R.id.indicator)
    InkPageIndicator indicator;
    @BindView(R.id.bannerpager)
    ViewPager bannerpager;
    @BindView(R.id.roomtypes)
    Spinner roomtypes;
    List<Hotel_TabBeans> listhotelbeans=new ArrayList<Hotel_TabBeans>();
    @Override

    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.hotel_detail);
        ButterKnife.bind(this);
        setSupportActionBar(hoteldetailedtoolbar);
        assert getSupportActionBar() != null;
        getSupportActionBar().setDefaultDisplayHomeAsUpEnabled(true);
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        hoteldetailedmethod();
        setupviewpager(hotelpager);
        hotelpager.setOffscreenPageLimit(1);
        hotelamentiestab.setupWithViewPager(hotelpager);
        hoteladapter = new HotelImages(getApplicationContext(), hotelimg);
        bannerpager.setAdapter(hoteladapter);
        ArrayList<String> roomlist = new ArrayList<>();
        roomlist.add("Rooms Types");
        roomlist.add("Standard");
        roomlist.add("Deluxe");
        roomlist.add("Luxury");
        ArrayAdapter<String> roomadapter = new ArrayAdapter<String>(getApplicationContext(), R.layout.spinner_detailed, R.id.spinnertext, roomlist);
        roomadapter.setDropDownViewResource(R.layout.spinner_dropdown);
        roomtypes.setAdapter(roomadapter);
    }

    @OnClick(R.id.spinnerbutton)
    public void spinnerbuttonclick() {
        roomtypes.performClick();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.hoteldetailed_menu, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.call:
                Intent intent = new Intent(Intent.ACTION_DIAL);
                intent.setData(Uri.parse("tel:0123456789"));
                startActivity(intent);
                return true;
            case R.id.share:
                Intent shareIntent = new Intent(Intent.ACTION_SEND);
                shareIntent.setType("text/plain");
                shareIntent.putExtra(Intent.EXTRA_SUBJECT, "CYStay");
                shareIntent.putExtra(Intent.EXTRA_TEXT, "Here live url will come");
                startActivity(Intent.createChooser(shareIntent,
                        "Share The Post"));
                return true;
            case android.R.id.home:
                onBackPressed();
                return true;
            default:
                return super.onOptionsItemSelected(item);
        }
    }

    private void setupviewpager(ViewPager pager) {
        TabsFragments tabsFragments = new TabsFragments(getSupportFragmentManager());
        tabsFragments.addfragment(new Hotel_tab(), "Hotel");
        tabsFragments.addfragment(new Hotel_tab(), "Room");
        pager.setAdapter(tabsFragments);
    }

    private void hoteldetailedmethod() {
        Display.showLoadingDialog(HotelDetails.this, "Loading...");
        final String hoteldetaildurl = Jsonurl.url + "hotel_details.php?rid=" + getIntent().getStringExtra("Roomid");
        Display.log(hoteldetaildurl);
        JsonObjectRequest hoteldetailedreq = new JsonObjectRequest(Request.Method.GET, hoteldetaildurl, null, new Response.Listener<JSONObject>() {
            @Override
            public void onResponse(JSONObject response) {
                try {
                    JSONArray hotelimagesarray = response.getJSONArray("hotel_images");
                    for (int i = 0; i < hotelimagesarray.length(); i++) {
                        JSONObject hotelimagearrayobj = hotelimagesarray.getJSONObject(i);
                        Hotel_image hotelimage = new Hotel_image();
                        hotelimage.setHotelimages(hotelimagearrayobj.getString("image"));
                        hotelimg.add(hotelimage);
                    }
                    int number = bannerpager.getChildCount();
                    if (number != -1) {
                        indicator.setViewPager(bannerpager);
                    }
                    JSONObject hoteldtails = response.getJSONObject("hotel_details");
                    getSupportActionBar().setTitle(hoteldtails.getString("hotel_name"));
                    hotelname.setText(hoteldtails.getString("hotel_name"));
                    hotelprice.setText(hoteldtails.getString("room_price"));
                    roomtype.setText(hoteldtails.getString("room_name"));
                    whatsmakes.setText(hoteldtails.getString("what_makes_special"));
                    needtoknow.setText(hoteldtails.getString("need_to_know"));
                    JSONArray ammarray=hoteldtails.getJSONArray("amenities");
                    for (int i = 0; i <ammarray.length() ; i++) {
                        JSONObject arrayobj=ammarray.getJSONObject(i);
                        Hotel_TabBeans tabeans=new Hotel_TabBeans();
                        tabeans.setAmenitimage(arrayobj.getString("img"));
                        tabeans.setAmenitiname(arrayobj.getString("name"));
                        listhotelbeans.add(tabeans);
                        Hotel_tab hotelTab=new Hotel_tab();
                        hotelTab.hoteltablist(listhotelbeans);
                    }
//                    hoteldatas.hoteldatamethod(listhotelbeans);
//                    Bundle listbundle=new Bundle();
//                    listbundle.putStringArrayList("hotelist",listhotelbeans);
//                    listbundle.putSerializable("hoye", (Serializable) listhotelbeans);
//                    Hotel_tab hoteltab=new Hotel_tab();
//                    hoteltab.setArguments(listbundle);

                } catch (JSONException e) {
                    e.printStackTrace();
                }
                hoteladapter.notifyDataSetChanged();
                Display.hideLoadingDialog();
            }
        }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                Display.log(error.toString());
                Display.hideLoadingDialog();
            }
        });
        hoteldetailedreq.setRetryPolicy(new DefaultRetryPolicy(500000, DefaultRetryPolicy.DEFAULT_MAX_RETRIES,
                DefaultRetryPolicy.DEFAULT_BACKOFF_MULT));
        AppController.getInstance().addToRequestQueue(hoteldetailedreq);
    }

}

这是我的片段activity:

public class Hotel_tab extends Fragment {
    public Hotel_tab() {
    }
    @BindView(R.id.hotel_tab_list)
    RecyclerView hotel_tab_list;
    Hotel_Tab_Layout hotel_tab_layout;

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        return inflater.inflate(R.layout.hotel_tab,container,false);
    }

    @Override
    public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        ButterKnife.bind(this,view);
        LinearLayoutManager hotelmanager = new LinearLayoutManager(getActivity(), LinearLayoutManager.VERTICAL, false);
        hotel_tab_list.setLayoutManager(hotelmanager);

    }
    public void hoteltablist(List<Hotel_TabBeans> msg){
        Display.toast(getActivity(),msg);//here is the null pointer exeception i am getting
    }
}

Answer 1

问题明确：
您希望在不将 Fragment 附加到 activity 的情况下获得 Context。

在解析来自服务器的成功响应时，您的代码如下所示：

Hotel_tab hotelTab=new Hotel_tab();
hotelTab.hoteltablist(listhotelbeans);

这意味着，您正在创建一个新的 Fragment 并在未附加到它的片段上调用方法 getActivity()。
您有 3 个选择：

如果你只想显示 toast，请在 Activity 内显示，而不是在 Fragment.
如果您确实需要在 Framgent 中执行此操作，请先使用 FragmentManager
或者将 Context 作为 Fragment 的函数 hoteltablist(...) 参数之一传递，如果你想在片段中显示 toast。

将日期从 Activity 传递到选项卡片段

pass date from Activity to tab frgament

android

android-fragments

fragment

android-tablayout